A self-propelled crop sprayer is a work machine which includes a storage tank for storing liquid chemical such as herbicides, pesticides, and fertilizers that are to be sprayed onto crops which are growing in a farm field. The liquid chemical within the storage tank is sprayed onto the crops growing in the field by use of a nozzle assembly secured to a number of booms as the crop sprayer is advanced along the rows of the field.
It is desirable for a crop sprayer to be utilized in conjunction with a number of varying field conditions. For example, the distance between rows of plants varies from field to field. Accordingly, it is desirable to provide a crop sprayer which is capable of adjusting the distance between its two right wheels and its two left wheels so as to allow the crop sprayer to be advanced down the rows associated with the field without damaging or destroying the crops planted therein. In order to accommodate this need, crop sprayers have heretofore been designed with adjustable-width axle assemblies. However, heretofore designed adjustable-width axle assemblies have a number of drawbacks associated therewith. For example, adjustable-width axle assemblies which have heretofore been designed are relatively mechanically complex and include a relatively large number of components thereby increasing the costs associated with manufacture and operation of the crop sprayer. Moreover, certain adjustable-width axle assemblies which have heretofore been designed are susceptible to mechanical failure thereby reducing the useful life of a number of the components associated with the crop sprayer.
It should be appreciated that it is often necessary to apply a number of different spray applications during the growth cycle of the crops in the field. For example, it may be necessary to apply a first spray application when the crops are relatively young, but then subsequent spray applications may be required after the crops have grown to a substantial height. It is desirable for the crop sprayer to be configured such that the frame or other components associated with the sprayer are positioned at a sufficient enough height above the field surface so as to clear the tops of the crops as the sprayer is advanced through the field.
It is therefore not uncommon for a farmer or farmer's cooperative to purchase two or more crop sprayers each of which has a different frame height for spraying crops of differing heights. However, this approach is relatively expensive and in some cases financially impossible for the farmer. In order to eliminate the need to purchase two or more different sprayers, a number of crop sprayers have been heretofore designed with adjustable-height mechanisms. However, such adjustable-height mechanisms which have heretofore been designed are generally mechanically complex and contain a number of expensive components such as hydraulic lifters along with the associated fluid components thereby increasing the costs associated with manufacture and operation of the crop sprayer.
It should also be appreciated that the crop sprayer must also be configured to easily and efficiently traverse varying surface topography when being operated in the field. For example, due to the long boom arms which crop sprayers require in order to cover many rows of crops with a single pass, a small change in the angle at which the chassis of the crop sprayer is oriented results in a large height change at the end of the boom arm thereby reducing crop clearance of the lowered boom arm. Hence, crop damage may occur if the boom arms sway back and forth across a relatively large distance as the crop sprayer encounters varying surface topography or if the boom arms are significantly moved upwardly and downwardly as the crop sprayer executes a turn. Moreover, the environment in which the crop sprayer is operated, a farm field, is particularly prone to having varying surface topography. In particular, it is not uncommon for a farm field to include areas called "washouts" in which soil has been displaced to create gradually sloping low spots. Advancement of a crop sprayer over such washouts, as well as turning the crop sprayer in the field, has the potential to undesirably shift the center of gravity and disturb the stability of the crop sprayer.
Moreover, the chemical storage tank must placed on the crop sprayer in a position which allows the tank to clear the crops as the sprayer advances through the field. The presence of the storage tank in such an elevated position, along with the fact that the liquid chemicals in the storage tank cause the storage tank to be extremely heavy, causes the crop sprayer to have a higher center of gravity relative to other types of work machines or a road traveling vehicle.
Hence, in order to manage the forces encountered by crop sprayers during operation thereof, a number of suspension systems have heretofore been designed. For example, hydraulic suspension systems have heretofore been designed that utilize a number of hydraulic cylinders which are provided in an attempt to dampen forces encountered by the crop sprayer. However, as described above, a crop sprayer is particularly sensitive to forces acting upon it due to its relatively high center of gravity and such heretofore designed suspension systems have not been capable of adequately stabilizing a crop sprayer as it is advanced and maneuvered within a farm field.
What is needed therefore is a crop sprayer which overcomes one or more of the above-mentioned drawbacks. What is further needed is a crop sprayer having an adjustable-width axle assembly which can be quickly and easily utilized to change the operational width of the crop sprayer. What is also needed is a crop sprayer having an adjustable-height chassis which can be quickly and easily utilized to change the operational height of the crop sprayer. What is moreover needed is a suspension system for a crop sprayer which is capable of adequately stabilizing a crop sprayer as it is advanced and maneuvered within a farm field.